Research on Cumulative Damage Characteristics of Rock Anchor Beam Concrete Supporting Structure by Blasting Vibration of Underground Powerhouse

Table 5

The relationship between the damage value of some unit monitoring points of the rock anchor beam along the axis of the powerhouse and the blast center distance.

Blast times	Regression analysis	Confidence level
	Relationship between damage value (y) and blast center distance (x)
2^nd	y = 0.0042x^4 − 0.0376x^3 + 0.0868x^2 − 0.0608x + 0.2082	0.9967
3^rd	y = 0.0115x^4 − 0.1312x^3 + 0.502x^2 − 0.8969x + 1.1599	0.9918
4^th	y = −0.0044x^4 + 0.0633x^3 −  0.3051x^2 + 0.3053x + 0.955	0.9897
5^th	y = 0.0094x^4 − 0.0849x^3 + 0.1634x^2 − 0.0732x + 1.004	0.9932